Heat exchanger



KUNlO FUJIE 3,473,603

Oct. 21, 1969 HEAT EXCHANGER 2- Sheets-Sheet 2 Filed Jan. 20, 1967INVENTOR KU-A/IO F IE ATTORNEY United States Patent 3,473,603 HEATEXCHANGER Kunio lFujie, Tokyo, Japan, assignor to Hitachi, Ltd, Tokyo,Japan, a corporation of .l'apan Filed Jan. 20, 1967, Ser. No. 610,647filaims priority, appiication Japan, Jan. 26, 1966, ll/4,041 Int. Cl.FZSf 13/12; F24h 3/06; FZSd 11/02 US. U. l65122 3 Claims ABSTRACT OF THEDESCLOSURE A rotary heat exchanger of the type equipped with a diskfriction fan having a hollow rotary shaft in which a pipe defining apath of a fluid to be subject to heat exchange is disposed in closeproximity to the inner wall of the hollow space in the hollow rotaryshaft so that upon rotation of the heat exchanger the pipe can be fullyimmersed in a liquid heat exchange medium accommodated in the hollowspace in the hollow rotary shaft.

This invention relates to improvements in heat exchangers of the typehaving a fan integrally incorporated therein, and more particularly to anovel rotary heat exchanger having a disk friction fan integrallyconstructed therewith.

Various kinds of heat exchangers have heretofore been proposed and foundtheir individual applications in the art of heat exchange. Among theseheat exchangers, forced air cooling heat exchangers designed for theforced air cooling of fluids have especially been preferred and findingapplications in various kinds of apparatus by virtue of their high heattransfer effectiveness. A typical conventional structure of such forcedair cooling heat exchangers is schematically illustrated in FIGS. 1 and2 in which it can be seen that the heat exchanger comprises a finnedheat exchanger section 4 formed by fixing a plurality of heat radiatingfins 3 to a pipe 2 which defines therein a path of a fluid 1, and a fansection 6 driven from a motor 5. In this type of heat exchanger, air isforcibly supplied from the fan section 6 toward the heat exchangersection 4 to increase the fin-side heat transfer of the pipe 2 forthereby enhancing the heat transfer effectiveness.

However the heat exchanger described above is not only costly to makedue to the fact that separate provision of the heat exchanger sectionand the fan section results in the high cost which is the sum of thecosts of these two sections, but also necessarily occupies a largeoverall volume due to the separate provision of these two sections. Theheat exchanger of this type is therefore unsuitable for use, forexample, as a domestic air conditioner or an automotive vehicle heaterfor which the small size is an essential demand. Further, with suchstructure, an attempt to increase the air velocity to thereby increasethe fin-side heat transfer will result in a remarkable increase in theresistance against the air flowing between the fins, thus necessitatinga larger fan power and a larger fan size and increasing the noise beyondan allowable limit. Moreover, the fan employed in the conventional heatexchanger of the type described above is either a propeller fan orcentrifugal fan which has an inherent problem of high noise and aconsiderable technical difliculty is encountered in the successfulreduction of the noise.

The present invention contemplates the provision of a forced air coolingheat exchanger of novel structure which is quite free from the defectsinvolved in the prior art forced air cooling heat exchangers asdescribed above and has for its primary object to provide a small-sized"ice and hence inexpensive heat exchanger yet having a high heattransfer effectiveness.

Another obejct of the present invention is to provide a heat exchangeroperating at quite a low noise level which is especially useful forapplications where a low noise is demanded.

A further object of the present invention is to provide a heat exchangerwhich can provide leak-free operation in cooling a fluid such as a highpressure gas.

Another object of the present invention is to provide a heat exchangerwhich, when for example used as an air conditioner, can suppy an airstream of large width corresponding to the desired air supply range andby which the air stream can be delivered in the form of slitlike flow asfrom the blow-out port of conventional air conditioners.

The heat exchanger according to the present invention is characterizedby the provision of a disk friction fan or more commonly a rotary heatexchange means integrally incorporated therein, said disk friction fanor rotary heat exchange means comprising a plurality of substantiallyequally spaced disks fixed to a rotary shaft at substantially rightangle with respect thereto for integral rotation with the rotary shaftso that the friction force between the faces of the disks rotating withthe rotary shaft and air or gas existing between the disks is utilizedto supply the desired cooling air or gas stream. The heat exchangeraccording to the invention has such a structure that the rotary shaft ofthe disk friction fan is made hollow in order that a pipe defining apath of a fluid to be subject to heat exchange can be disposed in thehollow space in the hollow shaft and a liquid heat exchange mediumhaving a good heat conductivity such, for example, as turbine oil can beaccommodated in the hollow space in the hollow shaft in heat exchangerelation with such fluid passing through the pipe. By virtue of theabove structure, the pipe through which the fluid to be subject to heatexchange passes can be fully immersed in the liquid heat exchangemedium, a high rate of heat transfer can be obtained between the fluidin the pipe and air or gas forcedly supplied by the disk friction fan,and the disks themselves of the disk friction fan can also act as heatradiating fins to further enhance the effect of heat transfer betweenthe fluid and the heat exchange medium.

Other objects, advantages and features of the present invention willbecome apparent from the following description with reference to theaccompanying drawings, in which:

W65. 1 and 2 are a schematic plan view and a schematic elevational view,respectively, of the prior art forced air cooling heat exchangerdescribed previousy;

16. 3 is a sectional view of the heat exchanger embodying the presentinvention, the section being taken on the line IlIllI in FIG. 4;

FIG. 4 is a sectional view taken on the line IVI V in PEG. 3;

FIG. 5 is an enlarged sectional view of a bearing portion in the heatexchanger of the invention; and

FIGS. 6 and 7 are perspective views showing some modified forms of apipe through which a fluid to be subject to heat exchange passes.

Referring to FIGS. 3 and 4, the heat exchanger embodying the presentinvention includes a rotary shaft 9 which is rotated by a drive shaft 8driven from a motor such, for example, as an electric motor (not shown).A plurality of substantially equally spaced disks 19 are fixed to therotary shaft 9 at substantially right angles with respect thereto toform a disk wheel 7 which is journalled at opposite ends in bearings 18and has an axial opening at one end thereof. The disk wheel 7 is partlysurrounded by a casing 11 so that, when the disk wheel 7 is rotated bythe motor, friction force developed between the disk faces and airexisting between the disks can cause forced flow of air from a direction12 towards a direction 13 as shown in FIG. 4.

In accordance with the present invention, the rotary shaft 9 is madehollow to define therein a hollow space 14, and a pipe 16 through whicha fluid 15 to be subject to heat exchange passes extends from theexterior into the axial opening of the disk wheel 7 through seal rings17 and is endless by spirally coiled in the hollow space 14 in therotary shaft 9 to leave the disk wheel 7 from the same axial opening ofthe latter. The spiral pipe 16 is suitably supported at a plurality ofportions in the hollow space 14 by support rings 21 of Teflon or likematerial, and a liquid heat exchange medium is filled up to a suitablelevel 19 in the hollow space 14 not exceeding the lower ends of the sealrings 17 in the stationary state of the rotary shaft 9 so that uponrotation of the disk wheel 7 the liquid is urged onto the inner face ofthe rotary shaft 9 as shown at 20 by the centrifugal force and thespiral pipe 16 can be sufliciently immersed in the layer of the liquid.The liquid heat exchange medium may preferably be a liquid such, forexample, as turbine oil which has a low viscosity and a high heatconductivity and is in itself inactive so that it does not participatein any chemical reaction and does not corrode metals.

From the structure as described above it will be apparent that uponrotation of the disk wheel 7, heat transfer between the fluid 15 flowingthrough the pipe 16 and the air forcedly flowed by the disk wheel 7 isconducted through the medium of the liquid 20, and the disks 10 actingalso as heat radiating fins further enhance the effect of the above heattransfer. As will be understood from FIG. 3, the liquid such as turbineoil is at a liquid level as shown at 19 not exceeding the lower ends ofthe seal rings 17 when the disk wheel 7 is at rest, while the liquid isthrown away to attach onto the inner face of the rotary shaft 9 as shownby the layer 20 due to the centrifugal force imparted thereto by therotation of the disk wheel 7. Thus there is no fear that the liquid ineither case would leak to the outside through the seal rings 17 throughwhich the pipe 16 extends into and out of the hollow space 14 in therotary shaft 9. Even if such leakage might tend to take place, anyleakage can be positively prevented by means as shown in an enlargedpartial view of FIG. 5. In FIG. is will be seen that a groove 23 is cutthrough a certain depth of the inner face of the journal portion 22 ofthe rotary shaft 9 and a passageway 24 is provided to providecommunication between the groove 23 and the hollow space 14 in therotary shaft 9. Therefore the liquid tending to leak from the hollowspace 14 through the inner seal ring 17 flows into the groove 23 whileeffectively lubricating the sealing contact portion between the outerperipheral surface of the seal ring 17 and the inner peripheral surfaceof the journal portion 22 of the rotary shaft 9 and flows back againinto the hollow space 14 through the passageway 24 by the action ofcentrifugal force. Thus any leakage of the liquid to the outside cannever take place. A plurality of fittings 25 are provided at the bottomportion of the casing 11 in order to fixedly mount the heat exchanger ona suitable member by means such as bolts 26.

In a heat exchanger according to the invention, a substantiallycylindrical pipe in the form of a hollow cylinder extends longitudinallywithin the rotary shaft defining the heat exchanger, said pipe forming acontinuous path for fluid to be subject to heat exchange. Thus theoutside diameter of the rotor shaft becomes correspondingly large;however, such outside diameter of the rotary shaft 9 would in no wayresult in a reduced quantity of air or gas flow because it is thecharacteristic of a disk friction fan that the disk thereof has a lowperipheral speed at a portion near the axis of the rotary shaft evenwith the rotary shaft of smaller outside diameter and the ability ofmoving the air or gas by the friction force is quite poor at suchportion of the disk.

It will be understood that the pipe 16 forming the path of the fluid 15may be bent in a zigzag or complex fashion as shown in FIGS. 6 and 7instead of the spiral shape as shown in FIG. 3. In addition to thoseshapes shown in FIGS. 3, 6 and 7, the pipe 16 may take any shape so longas it runs adjacent to the inner wall of the hollow rotary shaft insuflicient heat exchange relation with the liquid accommodated in thehollow space in the shaft. By so arranging, the quantity of the liquidheat exchange medium can be reduced, which leads to an advantage ofdecreasing the thermal capacity of the heat exchange medium. It will befurther understood that elimination of the casing will provide a heatexchanger structure which makes heat exchange while effecting anagitating operation.

It will be appreciated from the foregoing description that the heatexchanger according to the present invention having a disk friction fanintegrally constructed therewith has the following advantages over priorart forced air cooling heat exchangers as described above:

(1) The heat exchanger can be made to a remarkably small-sized andlight-weight unit. When compared with the prior art forced air coolingheat exchanger such as aforementioned type having the same heat flowrate and air flow rate, the inventive heat exchanger has a 3 volume, hasa relatively simpler structure and is less expensive.

(2) It was ascertained that the relative velocity of air passing betweenthe fins of the heat exchanger of the invention could be made more thanabout four times that of the prior art heat exchanger such asaforementioned type, under the condition that the blowing power is thesame for both. It was therefore made certain that the rate of heattransfer between the fins (disks) and air in the inventive heatexchanger could be made more than about two times that of the prior artheat exchanger.

(3) Noise level is unquestionably low because the fan employed thereinis a disk friction fan.

(4) A fluid to be brought into heat exchange relation with aircontinuously supplied by the disk friction fan is arranged to flowthrough the spiral pipe extending from the exterior into the rotaryshaft. Therefore there is utterly no possibility of leakage of the fluidregardless of the kind of the fluid whether it is a liquid or a gas andregardless of pressure of such fluid. This means that the heat exchangerof the invention can for example be safely operated for the cooling of ahigh pressure refrigerant for air conditioning condensers andevaporators.

(5) Since the fan is constructed by fixing a plurality of disks on arotary shaft and therefore it can be suitably extended in the axialdirection to meet a particular requirement, the blow-out port can bemade to a slit-like form conforming to the blow-out port of airconditioners or heaters. Thus the heat exchanger can be easily designedto suit the shape of air conditioners or heaters and can be reasonablyaccommodated in air conditioning or heating apparatus to provide compactand small-sized ap paratus of the above kinds.

(6) The liquid such, for example, as Water, oil, and non-freeze liquidetc. enclosed in the rotary shaft can not escape outwardly by beingintercepted by the leak-proof means as described previously, and thatportion of the liquid oozing out to the seal ring portion effectivelylubricates the sealing contact between the seal ring and the innerperipheral face of the hollow journal portion of the rotary shaft.

(7) Gases other than air can be supplied by the disk friction fan and,if so required, it is also possible to feed a liquid by operating thedisk friction fan as a pump. Thus the heat exchanger of. the inventioncan not only be used as air conditioners or automotive vehicle heaters,

6 but also as heat exchangers in chemical industry, hygienic (4) meansfor causing rotation of said hollow rotary industry and various otherindustries. shaft.

What is claimed is: 2. A heat exchanger according to claim 1, in whichl. A heat exchanger, comprising: said pipe means defining a path for afluid to be subject (1) disk friction fan means including a hollowrotary to heat exchange and extending along said hollow rotary shaft anda plurality of substantially equally-spaced 5 shaft in close proximityto the inner wall of said rotary disks mounted on said hollow rotaryshaft at subshaft is made to a spiral form. stantially right angles tothe axis thereof, said hollow 3. A heat exchanger according to claim 1,in which rotary shaft and disks mounted thereon forming a disk said pipemeans defining a path for a fluid to be subject wheel, and a housingsurrounding at least a portion to heat exchange and extending along saidhollow rotary of said disk wheel, said housing serving to guide flow 10shaft in close proximity to the inner wall of said rotary of fluidsurrounding said heat exchanger through said shaft is made to a Zigzagform. disk wheel during rotation thereof, (2) pipe means defining a pathdescribing a hollow References flied cylinder disposed generallylongitudinally within said UNIT STATES PATENTS hollow rotary shaft for afluid to be subjected to heat exchange, said pipe means extending fromthe exterior i 165122 X odgdon 165-92 In) an axial opening of sald diskwheel, through at 2 616 669 11/1952 olcott 165 92 least one seal ring,in close proximity to the inner 2991979 7/1961 1 165 Wall of said hollowrotary shaft, n (3) a liquid heat exchan e medium contained in a 3OG968311/1961 Gnesglhuber 92 3 3,022,046 2/1962 Breig 1659O space within saidhollow rotary shaft, the level of said liquid heat exchange medium, inthe stationary state ROBERT A OLEARY Primary Examiner of said diskfriction fan means, not exceeding the lower rnost portion of said sealring, whereby said 25 STREULE, Asslstant Examlner pipe means isimmersed, over a major portion thereof,

within said liquid heat exchange medium as it is impelled outwardlyagainst the inner Wall of said 165 9O hollow rotary shaft upon rotationthereof, and

